A conventional gas lighter (e.g., pressure actuation gas lighter) is shown in FIGS. 1 and 2. The gas lighter comprises an elongated handle 10 including a hollow cylinder 11 extended outwardly a predetermined distance, the cylinder 11 including a nozzle 12 having one end 121 with a large diameter abutted on the cylinder 11, and the other end 122 with a small diameter open to outside. Within the handle 10 there are provided a gas fuel reservoir 13 having one end in fluid communication with a valve 14. The valve 14 comprises a hollow seat 141, a sleeve 142 having outer threads put on a forward portion of the seat 141, an elongated mouth 143 extended from a bottom of the seat 141 through the bore of the sleeve 142 and a forward opening 144, and an enlargement 145 formed on a forward end of the mouth 143 and inserted into a hose 151. An actuation member 15 is pivotably provided between the enlargement 145 and the sleeve 142 with the mouth 143 passed.
A peripheral projection 146 is formed around the mouth 143 inside the sleeve 142. A spring 148 is put on the mouth 143 to be in contact with the projection 146. A gasket 147 is also put on the mouth 143 to be in contact with one end of the spring 148. Both spring 148 and gasket 147 are disposed within the sleeve 142. A side aperture 149 is formed on the mouth 143 adjacent the seat 141. A leakproof nut 16 is provided at the bottom of the mouth 143 proximate a bottom of the seat 141.
As shown in FIG. 2, pressing the actuation member 15 will lift the enlargement 145 from the leakproof nut 16 at the bottom of the mouth 143 and thus open a hole at the bottom of the seat 141. Next, gas may flow from the gas fuel reservoir 13 to the cylinder 11 (i.e., the nozzle 12) through the hose 151 as indicated by arrows. As an end, a lighting tube (not shown) is activated to burn as gas flows to it.
However, the prior art suffered from a disadvantage. For example, the gas lighter may still burn after cutting off the gas supply path. In detail, after something has been burned by igniting the gas lighter a user may release the actuation member 15 to lower the mouth 143 to its normal position. At this time, it is supposed that gas will not flow from the gas fuel reservoir 13 to the nozzle 12. However, this is not true. As shown in FIG. 1, a releasing of the actuation member 15 will lower the mouth 143 to its normal position and thus cause the leakproof nut 16 at the bottom of the mouth 143 to block the gas path at the bottom of the seat 141 (i.e., stop gas from flowing out of the gas fuel reservoir 13). But the gasket 147 adjacent the forward opening 144 inside the sleeve 142 still blocks the forward opening 144 because the gasket 147 is urged by the elasticity of the spring 148. As such, remaining gas in the hose 151 cannot flow back due to insufficient momentum and pressure. Instead, remaining gas continues to flow along the hose 151 to the nozzle 12. That is, remaining gas will continue to flow to the nozzle 12 in the cylinder 11 since gas pressure in the hose 151 is larger than outside pressure (i.e., atmospheric pressure). Such flow will finally stop when gas pressure in the hose 151 drops below the atmospheric pressure. The above has described the reason why the gas lighter still burns after cutting off the gas supply path. Unfortunately, it may result in fires causing property damage and injury to people. Hence, a need for improvement exists.